Rocker Arm for vertical roller mill
One-stop service covering design, process and manufacture
Weight: 5~30 T
Main Materials: ZG270-500、ZG30SiMnMo
Compatible brands: Various types of vertical mills.
Applicable: Steel slag vertical mill, mineral powder vertical mill, coal vertical mill, etc.
The rocker arm of the vertical roller mill is a core load-bearing component of the vertical mill, used to connect the VRM rollers to the main frame. Its function is to transfer pressure to the grinding rollers through hydraulic loading, achieving efficient grinding. Our rocker arm is manufactured using high-strength cast steel or ductile iron, featuring excellent fatigue resistance, impact resistance, and long-term stability.
Scope of Application:
- Vertical raw mill
- Cement vertical mill and slag vertical mill
- Mill for coal powder
- Industrial solid waste vertical mill (steel slag, tailings)
Advantages of rocker arm
High-strength materials
High wear resistance, high toughness, and fatigue resistance, suitable for heavy-duty working conditions.
High precision
NC machining ensures high precision of hole positions, axes, and installation surfaces.
100% non-destructive testing
Full inspection system, ensuring higher quality.
Long service life design
Strengthened by heat treatment, with a lifespan significantly higher than that of ordinary manufacturers.
Price advantage
Replacement of imported parts, with high cost-effectiveness.
Fast delivery
Well-established batch production system, with short delivery times.
Manufacturing process of rocker arm
1. Raw material selection
The main body of the rocker arm is generally made of high-strength ductile iron (such as QT700-2, QT800-4) or high-quality cast steel (such as ZG30SiMnCrMo, ZG42CrMo). The raw materials undergo spectral analysis to ensure stable chemical composition.
Material Requirements:
- High fatigue strength, good impact resistance
- Excellent casting properties, reducing shrinkage cavities and gas pores
- High fracture toughness and wear resistance
2. Mold design & manufacturing
The rocker arm is large in size and has a complex structure. The molds are mostly made of wooden molds or resin sand molds. To prevent shrinkage cavities and shrinkage porosity, control stress concentration and deformation, and ensure internal density.
- Three-dimensional modeling, conducting CAE pouring simulation (MAGMA, ProCAST)
- Designing the gating system, risers, and cold runners layout
- Mold processing and assembly
- Model repair and checking dimensions
3. Molding (melting + pouring)
Melting
- Melting molten steel/iron in a medium-frequency furnace
- Online sampling and spectroscopic analysis
- Controlling the contents of C, Si, Mn, Cr, and Mo
- Controlling the temperature (generally 1500–1580℃)
Pouring
- Selecting resin sand molding or lost foam casting
- Using top or bottom pouring systems
- Controlling the pouring speed to avoid slagging and sand inclusion
- Installing heating and insulation risers to improve density
After pouring, it cools naturally, usually requiring 12–36 hours (depending on the weight of the ram).
4. Sand Cleaning & Initial Grinding
After the casting cools down, the following steps are carried out:
- Sand removal and cleaning (using shot blasting)
- Removal of risers and gates
- Rough grinding of burrs and flash
- Appearance inspection (checking for cracks and sand holes)
Usually, a shot blasting machine is used to achieve a Sa 2.5 cleanliness level.
5. Heat treatment
Internal casting stress and welding stress exist in the cast armature, so heat treatment is necessary.
Cast iron armature
- Stress relief annealing: 550–650℃
- Hold for 2–6 hours
- Furnace cooling
Cast steel armature
- Normalizing + tempering: 850–950℃
- Hold
- Air cooling or furnace cooling
6. Finishing
Depending on the model of the vertical mill, the processing accuracy requirements are generally as follows:
- Flatness ≤ 0.05 mm/m
- Center position of holes ≤ 0.05 mm
- Axiality ≤ 0.03 mm
Drilling
- Hydraulic cylinder hinge holes
- Pin shaft holes
- Position of grinding roller suspension points
Milling of key mating surfaces
- Installation surface of bearing seat
- Sealing surface
- Sliding surface
Surface treatment
- Sandblasting
- Spraying of primer (epoxy zinc-rich)
- Spraying of topcoat (polyurethane)
7. Non-destructive Testing (NDT)
Ensure that the rocker arm quality meets the high-load requirements of the vertical mill.
8. Assembly fitting and finished product inspection
Ensure that the rocker arm, grinding roller, hydraulic cylinder, and main frame are fully compatible.
9. Packaging and Shipping
The general weight of the rocker arm is approximately 2-5 tons. For export packaging, a metal frame + supporting wooden pads are commonly used. The following steps are required:
• Installation of a wooden base plate
• Wrapping with film + rust-proof paint protection
• Factory quality inspection report (including UT/MT/dimension testing)
• Material certificate
• Processing drawings (not necessary)
AGICO CEMENT – steel casting supplier
High end casting capability
- 30-60 ton medium frequency furnace melting, high purity of steel liquid
- CAE casting simulation to avoid shrinkage, slag inclusion, and porosity
- Resin sand molding+large insulation riser, resulting in high density
- Single piece weight can reach 1-20 tons, meeting the needs of large vertical mills
Precision machining centers
- Five sided machining center, floor boring and milling machine, and complete CNC machining equipment
- The accuracy of hinge holes, axis positions, and installation surfaces can reach:
- Aperture accuracy: H7-H8
- Coaxiality: ≤ 0.03 mm
- Flatness: ≤ 0.05 mm/m
Full process non-destructive testing
- UT ultrasonic testing
- MT magnetic particle testing
- Three coordinate dimension detection
- Material Chemical Composition Report
- Mechanical performance test report
Strong adaptability
- Material options: ZG30SiMnCrMo, ZG42CrMo, QT700-2, QT800-4, etc
- Can be used as OEM/ODM support
- Provide structural optimization, lifespan extension and upgrade solutions
- Support old rocker arm surveying, reverse engineering, and replacement of imported parts
The FAQ of rocker arm
Q1: Can you customize the rocker arm according to the drawing?
Sure, we support OEM/ODM and can also perform reverse mapping based on samples.
Q2: Can you replace the rocker arms of different vertical mills?
Support, including models such as Loesche, OK, POLYSIUS, Gebr, Pfeiffer, etc.
Q3: How are your products packaged? Is it suitable for export?
Packaged with a steel frame and wooden base, suitable for sea transportation, impact resistant, moisture-proof, and rust proof.
Q4: Is the quality inspection report provided with the goods?
Provide material certification, UT/MT testing reports, size reports, and heat treatment records.
